In a typical motor vehicle, a door latch is mounted to a vehicle door. The door latch includes a fork-bolt that engages or grasps a striker mounted on the vehicle body structure. A latch release mechanism includes a releasable pawl member that selectively engages the fork-bolt/latch to prevent disengagement of the fork-bolt from the striker. An exterior handle is mounted on an outer side of the door, and an interior handle is mounted on an inner side of the door. The exterior and interior handles are connected to the latch mechanism utilizing a rod, Bowden cable, interfacing cam surfaces, or other suitable mechanical linkage. The purpose of the door handles is to transfer motion and force from the vehicle operator to the latch release mechanism (e.g. pawl) within the latch to release the fork-bolt/latch from the striker. Once the fork-bolt/latch is released from the striker, the door is free to open.
Vehicle door latch mechanisms typically include a locking mechanism that may be within the latch mechanism. The purpose of the locking mechanism is to mechanically couple or de-couple the handles from the pawl.
When an automobile door latch mechanism is in an unlocked state, the exterior handle is connected to the pawl. When the exterior handle is operated (i.e. manually moved by a user), the pawl is operated, and the fork-bolt/latch releases from the striker, allowing the door to be opened. When the automobile door latch is in the unlocked state, the interior release (typically a movable handle or lever) is mechanically connected to the latch release mechanism. Thus, when the interior handle is operated (moved), the fork-bolt/latch will release from the striker.
When a vehicle door latch mechanism is in the locked state, the exterior handle is mechanically disconnected from the latch release mechanism. When the exterior handle is operated, no motion is transferred to the pawl, and the fork-bolt/latch will not release from the striker. Depending upon the requirements for a particular vehicle, the interior handle may be connected or disconnected from the latch release mechanism when the latch is in the locked stated. Thus, movement of the interior handle will release the fork-bolt/latch from the striker in some vehicles even though the door latch is in a locked state. However, in other vehicles, the interior handle is disconnected when the door latch is in a locked state such that actuation/movement of the interior handle does not cause the fork-bolt/latch to release from the striker.
Vehicle door latch mechanisms can be locked/unlocked in various ways. For example, the vehicle door may include a key cylinder on an exterior of the vehicle that is mechanically connected to the locking mechanism within the latch such that rotation of the key cylinder locks/unlocks the locking mechanism. Vehicle doors may include a moveable lock member such as a lever on an interior side of the door that is mechanically connected to the locking mechanism within the latch. Movement of the interior lock member causes the locking mechanism within the latch to lock/unlock. Vehicles may include an interior and/or exterior power lock control, whereby an electrical or pneumatic actuator operates the lock mechanism inside the latch to thereby lock/unlock the lock mechanism. Powered door locks may be actuated by buttons or the like inside a vehicle, or by a remote fob.
A known type of vehicle door latch mechanism includes a lever internal to the latch that connects (unlock state) or disconnects (lock state) the exterior door handle from the latch release mechanism/pawl. The internal lock lever is directly or indirectly connected to an over-center spring such that the lock lever resides in either the lock or unlock state/position. The lock lever can be moved between the locked and unlocked state/position by operation of a key cylinder on an exterior of the vehicle, operation of a mechanical interior lock member, and/or operating an interior or exterior power lock control button or switch. In known door latch mechanisms, the lock lever only moves between the locked and unlocked positions/states in response to a user input or “request” to change the lock state/position of the lock lever. The user request may comprise actuation of a mechanical lock member, power lock control button/switch inside the vehicle, or actuation of a wireless fob. In this type of door latch system, the lock lever does not normally change state (lock or unlock), if the vehicle is subject to a side impact causing a transverse acceleration to the side.